The invention relates in general to the use of services offered to users of a telecommunication network using the services via individual terminals and particularly to a method for easily bringing the continuously changing and developing services of an intelligent telecommunication network within the reach of private users. The invention also relates to a telecommunication system wherein changing services are offered to users, and a terminal for such a system.
Intelligent network (IN) is a known concept in telecommunication technology and it generally refers to a telecommunication network control method wherein the services offered by a telephone network have been made more versatile than in the ordinary public switched telephone network (PSTN). Basic services of a modern intelligent network include call transfers and alternative billing, for example. It is also possible to include in a PSTN switching centre a service that supports user mobility. It is typical of intelligent networks that the switching centres include some kind of programming facility with which the network operators or somebody authorized by them can alter the operation and services of the network without changing a significant part of the system software of the switching centre. It is presumable that in the future the amount and range of telecommunication services offered will be considerably higher and wider, thereby making those services an important factor in the competition between network operators.
Services provided by intelligent networks can be divided into free services and services liable to charges. Free services are accessible to all subscribers of the network and instructions for their use are published in announcement and information material, such as telephone directories and customer newsletters. Use of services liable to charges normally requires that some kind of an agreement be signed by the user and the service provider. The service provider is not necessarily the same as the company maintaining the network but the service provider has got a programming connection to the switching centre(s) of the intelligent network. When the agreement has been signed, the service provider programs the switching centre to accept the service in question for that particular subscriber ID code.
In modern intelligent networks, the free and non-free services are usually activated and controlled by the user issuing commands from his terminal (phone) which are directed via the network to a command interpreter in the switching centre and therefrom to the unit controlling the operation of the switching centre. The switching centre responds by enabling or disabling a certain service (having checked that the user is authorized to use the service in question, if the service is liable to charges) or by performing some other function required by the user. As the interfaces of most of the phones in PSTN networks comprise only a handset and a dial pad, the commands issued by users are usually series of digits with occasional special characters, like # and *. Presses of buttons are transformed into dual-tone multifrequency (DTMF) signals in the network. Certain networks, such as the integrated services digital network (ISDN), have, in addition to the specific digit and character sequences, special signalling practices that can be used for transferring commands from the users to the switching centre of the intelligent network.
As the number of services increases and the supply becomes more versatile, it is presumable that the currently used commands consisting of character sequences will become impractically long. Even today, users have to memorize several rather long command sequences in conjunction with certain services. Such services include voice mail and the use of bank services by phone, wherein users have several options the commands for which they have to learn by heart or look them up in the operating instructions of the service every time they use the service in question.
One solution to the problem caused by the diversity of services and commands was to include in the phone special function keys so that standard functions associated with those keys could replace some of the digit sequence commands. There is, however, the problem that the services offered may change and develop very rapidly as both the network operators and the service providers compete for market shares and develop their operations. Solutions based on the technical implementation of the telephone quickly become outdated and it is probable that the users are not willing to acquire a new terminal very often.